A new species and a new combination in Micrechites (Apocynaceae: Apocyneae) from China, with updates on M. jacquetii from Laos and Vietnam

Micrechites xiangguiensis A.Liu, X.L.Yu & G.W.Hu (Apocyneae, Apocynaceae), a new species from China, is described and illustrated herein. Morphologically, the new species closely resembles M. jacquetii Pierre from Laos and Vietnam, but can be distinguished by its lanceolate calyx lobes, ovary with long silvery white trichomes at the apex, disk extending to nearly half the length of the ovary, and longer flower buds. Additionly, the Chinese material previously identified as M. jacquetii is revised and recognized as Micrechites oliganthus (Tsiang) Miao Liao, Cai F.Zhang & G.W.Hu, comb. nov., based on Ichnocarpus oliganthus Tsiang. This species is here reinstated as a distinct species from the synonymy of M. jacquetii due to notable differences in flower color, the presence of glands at the base of the inner calyx, the presence of trichomes on the ovary, and disk length. Revised descriptions of M. jacquetii and M. oliganthus are provided, along with an updated key to the Chinese species of Micrechites . While M. oliganthus has recently been recorded in southern China, including Fujian, Jiangxi and Hong Kong, M. jacquetii is known solely from type specimens collected over a century ago. Its apparent absence in recent surveys suggests it may have gone extinct due to historical overexploitation for rubber extraction. This study highlights the critical role of taxonomic research in documenting species diversity and providing essential data for biodiversity conservation.